反应详情

Added 3′-fluoroacetanilide (3.06 g, 20 mmol) cautiously to concentrated sulfuric acid (6 mL) at 5° C. To the resulting solution, added fuming nitric acid (1.05 mL, 25 mmol) dropwise while maintaining temperature at 5–10° C. After 30 min, added ice (50 g), later diluted with water (100 mL) and extracted with EtOAc (2×100 mL). The combined organic layers were washed with saturated NaHCO3 and brine, dried over anhydrous Na2SO4 and concentrated to give the crude product (4.0 g) as a mixture of isomers (1:1.4 ratio of 4′-nitro/2′-nitro). The desired isomer, 3′-flouro-4′-nitroacetanilide, was isolated by flash chromatography (DCM-5% MeOH/DCM) in low yield (1.2 g, 30%) as a yellow solid. 1H-NMR (CDCl3): δ 8.08 (1H, app t), 7.82 (1H, dd), 7.41 (1H, br s), 7.21 (1H, m), 2.25 (3H, s).

1. temperaturewhile maintaining temperature at 5–10° C
2. extractionextracted with EtOAc (2×100 mL)
3. washThe combined organic layers were washed with saturated NaHCO3 and brine
4. dry with materialdried over anhydrous Na2SO4
5. concentrationconcentrated
6. customto give the crude product (4.0 g)
7. additionas a mixture of isomers (1:1.4 ratio of 4′-nitro/2′-nitro)